Bystander cell death and stress response is inhibited by the radical scavenger α(1)-microglobulin in irradiated cell cultures

Alpha-particle irradiation of cells damages not only the irradiated cells but also nontargeted bystander cells. It has been proposed that the bystander effect is caused by oxidants and free radicals generated by the radiation. Recent studies have shown that α(1)-microglobulin protects against cell damage caused by oxidants and free radicals. Using a novel experimental system that allows irradiation of 0.02% of a human hepatoma monolayer, leaving 99.98% as bystander cells, we investigated the influence of oxidative stress and the cell-protective effects of α(1)-microglobulin during α-particle irradiation. The results showed an increase in cell death in both irradiated cells and bystander cells. A significant increase in apoptosis, oxidation markers and expression of the stress response genes heme oxygenase 1, superoxide dismutase, catalase, glutathione peroxidase 1, p21 and p53 were observed. Addition of α(1)-microglobulin reduced the amount of dead cells and inhibited apoptosis, formation of oxidation markers, and up-regulation of stress response genes. The results emphasize the role of oxidative stress in promoting bystander effects. Furthermore, the results suggest that α(1)-microglobulin protects nonirradiated cells by eliminating oxidants and free radicals generated by radiation and imply that α(1)-microglobulin can be used in radiation therapy of tumors to minimize damage to surrounding tissues.     

A1M/α1-Microglobulin Protects from Heme-Induced Placental and Renal Damage in a Pregnant Sheep Model of Preeclampsia

Preeclampsia (PE) is a serious pregnancy complication that manifests as hypertension and proteinuria after the 20^th gestation week. Previously, fetal hemoglobin (HbF) has been identified as a plausible causative factor. Cell-free Hb and its degradation products are known to cause oxidative stress and tissue damage, typical of the PE placenta. A1M (α₁-microglobulin) is an endogenous scavenger of radicals and heme. Here, the usefulness of A1M as a treatment for PE is investigated in the pregnant ewe PE model, in which starvation induces PE symptoms via hemolysis. Eleven ewes, in late pregnancy, were starved for 36 hours and then treated with A1M (n = 5) or placebo (n = 6) injections. After injections, the ewes were re-fed and observed for additional 72 hours. They were monitored for blood pressure, proteinuria, blood cell distribution and clinical and inflammation markers in plasma. Before termination, the utero-placental circulation was analyzed with Doppler velocimetry and the kidney glomerular function was analyzed by Ficoll sieving. At termination, blood, kidney and placenta samples were collected and analyzed for changes in gene expression and tissue structure. The starvation resulted in increased amounts of the hemolysis marker bilirubin in the blood, structural damages to the placenta and kidneys and an increased glomerular sieving coefficient indicating a defect filtration barrier. Treatment with A1M ameliorated these changes without signs of side-effects. In conclusion, A1M displayed positive therapeutic effects in the ewe starvation PE model, and was well tolerated. Therefore, we suggest A1M as a plausible treatment for PE in humans.     

Fatness but Not Fitness Relative to the Fat-Free Mass Is Related to C-Reactive Protein in 18 Year-Old Adolescents

Introduction

The interaction between fatness, fitness, and C-reactive protein (CRP) in adolescents is not well characterized but may be important to prevent low grade inflammation. The purpose of this study was to assess the relationship between adiposity, different expressions of fitness, and CRP in late adolescence using direct measures of fitness and fatness.

Methods

Anthropometric measurements were taken on 245 eighteen-year-old participants (116 girls). Fasting CRP, glucose, and insulin were measured and homeostatic model assessment (HOMA) calculated. Body composition was estimated via dual energy X-ray absorptiometry. Fitness was assessed with maximal oxygen uptake (VO₂max) during a treadmill test and also expressed relative to the fat-free mass (VO₂max_FFM).

Results

Prevalence of overweight/obesity based on body mass index (BMI) was 20.7% and 25.6% among girls and boys, respectively (p = 0.407), but 42.5% and 58.1% when based on body fat percentage (%fat, p = 0.015). Higher proportion of boys (81.3%) than girls (54.5%) were highly fit (p<0.001), but the percentage of girls with high levels of CRP was greater (12.1% vs 6.2%, p = 0.028). Adiposity, indicated with BMI, waist circumference, fat mass, android fat mass (aFM), or %fat, was positively associated with CRP independent of VO₂max (r = 0.13-0.18, p<0.05) and VO₂max_FFM (r = 0.24-0.32, p<0.001). VO₂max, was negatively associated with CRP independent only of BMI and waist circumference (r = -0.21, p = 0.001), but not %fat, fat mass or aFM (r = -0.08 to -0.12, p>0.05). VO₂max_FFM was unrelated to CRP with (r = -0.07 to -0.11, p>0.05) or without (r = -0.10, p = 0.142) adjustment for adiposity. Additional adjustment for HOMA did not change any of the relationships, although the coefficients were attenuated.

Conclusions

Fatness has a greater association with CRP than fitness in late adolescence. However, VO₂max_FFM, which is truly independent of adiposity, is unrelated to CRP, indicating that the effects of fitness might be mediated via the fatness component embedded in fitness expressed relative to body mass.     

A prospective study on insect bite hypersensitivity in horses exported from Iceland into Switzerland

Background

Insect bite hypersensitivity (IBH) is an IgE-mediated dermatitis caused by bites of Culicoides spp., which occurs frequently in horses imported from Iceland to continental Europe. IBH does not occur in Iceland because Culicoides species that bite horses are not present. However, Simulium vittatum (S. vittatum) are found in Iceland. In Europe, blood basophils from IBH-affected horses release significantly more sulfidoleukotrienes (sLT) than those from healthy controls after in vitro stimulation with Culicoides nubeculosus (C. nubeculosus) and S. vittatum. Aims of the study were: (I) using the sLT release assay, to test if horses living in Iceland were sensitized to S. vittatum and (II) to determine in a longitudinal study in horses imported from Iceland to Switzerland whether the sLT release assay would allow to predict which horses would develop IBH.

Results

Horses in Iceland, even when living in high S. vittatum areas, were usually not sensitized to S. vittatum or C. nubeculosus. Incidence of IBH in the 145 horses from the longitudinal study was 51% and mean time until IBH developed was 2.5?±?1 year. Before import and after the first summer following import, there were no significant differences in sLT release between the endpoint healthy (H) and IBH groups. After the 2nd summer, when the number of clinically affected horses increased in the endpoint IBH group, a significantly higher sLT release after stimulation with C. nubeculosus but not with S. vittatum was observed. After the 3rd and 4th summer, the endpoint IBH group had a significantly higher sLT release with C. nubeculosus and S. vittatum than the endpoint H group. Some of the horses that remained healthy became transiently positive in the sLT release assay upon stimulation of their peripheral blood leucocytes with C. nubeculosus.

Conclusions

Horses in Iceland are not sensitized to S. vittatum. In horses that develop IBH, sensitization to S. vittatum is secondary to sensitization to C. nubeculosus and probably a result of an immunological cross-reactivity. A sLT release assay cannot be used to predict which horses will develop IBH. A transient positive reaction in the sLT release assay observed in horses that remained healthy suggests that immunoregulatory mechanisms may control an initial sensitization of the healthy horses.

     

X-ray crystal structure of Vibrio alkaline phosphatase with the non-competitive inhibitor cyclohexylamine

BackgroundPara-nitrophenyl phosphate, the common substrate for alkaline phosphatase (AP), is available as a cyclohexylamine salt. Here, we report that cyclohexylamine is a non-competitive inhibitor of APs.MethodsCyclohexylamine inhibited four different APs. Co-crystallization with the cold-active Vibrio AP (VAP) was performed and the structure solved.ResultsInhibition of VAP fitted a non-competitive kinetic model (K_m unchanged, V_max reduced) with IC₅₀ 45.3 mM at the pH optimum 9.8, not sensitive to 0.5 M NaCl, and IC₅₀ 27.9 mM at pH 8.0, where the addition of 0.5 M NaCl altered the inhibition to the level observed at pH 9.8. APs from E. coli and calf intestines were less sensitive to cyclohexylamine, whereas an Antarctic bacterial AP was similar to VAP in this respect. X-ray crystallography at 2.3 Å showed two binding sites, one in the active site channel and another at the surface close to dimer interface. Antarctic bacterial AP and VAP have Trp274 in common in their active-sites, that takes part in binding cyclohexylamine. VAP variants W274A, W274K, and W274H gave IC₅₀ values of 179 mM, 188 mM and 187 mM, respectively, at pH 9.8.ConclusionsThe binding of cyclohexylamine in locations at the dimeric interface and/or in the active site of APs may delay product release or reduce the rate of catalytic step(s) involving conformational changes and intersubunit communications.General significanceCyclohexylamine is a common chemical in industries and used as a counterion in substrates for alkaline phosphatase, a clinically important and common enzyme in the biosphere.     

Pseudomonas syringae isolated in lichens for the first time: Unveiling Peltigera genus as the exclusive host

Pseudomonas syringae is a bacterial complex that is widespread through a range of environments, typically associated with plants where it can be pathogenic, but also found in non-plant environments such as clouds, precipitation, and surface waters. Understanding its distribution within the environment, and the habitats it occupies, is important for examining its evolution and understanding behaviours. After a recent study found P. syringae living among a range of vascular plant species in Iceland, we questioned whether lichens could harbour P. syringae. Sixteen different species of lichens were sampled all over Iceland, but only one lichen genus, Peltigera, was found to consistently harbour P. syringae. Phylogenetic analyses of P. syringae from 10 sampling points where lichen, tracheophyte, and/or moss were simultaneously collected showed significant differences between sampling points, but not between different plants and lichens from the same point. Furthermore, while there were similarities in the P. syringae population in tracheophytes and Peltigera, the densities in Peltigera thalli were lower than in moss and tracheophyte samples. This discovery suggests P. syringae strains can localize and survive in organisms beyond higher plants, and thus reveals opportunities for studying their influence on P. syringae evolution.     

Correction to: Development and Validation of Arc Nanobodies: New Tools for Probing Arc Dynamics and Function

Neurochemical Research -